1. Field of Invention
The invention relates to a fixing device in an image forming apparatus for fixing a toner image transcribed on paper by heating paper on which an image formed by supplying a toner in accordance with an electrostatic latent image formed on a photosensitive drum in a developing device, is transcribed. Particularly, the invention relates to a fixing device capable of removing curl caused in the paper in the fixing device in fixing a toner image by smoothly changing a feed direction of the paper toward a discharge roller in a fixing device.
2. Description of Related Art
There have conventionally been proposed various image forming devices, such as a laser printer or the like, adopting a so-called electronic photographing system. For example, an image forming device having a paper feeding device, a laser scanning device, a toner supplying device, a developing device, a fixing device and the like in gross classification, is disclosed in the specification and the drawings of Japanese Printed Patent Document No. 9-319201. According to such an image forming device, an electrostatic latent image is formed on the surface of a photosensitive drum in the developing device in accordance with image data provided by the laser scanning device, a toner image is formed on the photosensitive drum by supplying a toner in accordance with the electrostatic latent image from the toner supplying device, the toner image is transcribed by the cooperation of a transcribing roller and the photosensitive drum on a paper transferred from the paper feeding device into the developing device and thereafter, the toner image is fixed by heating the paper by the fixing device.
According to the fixing device, paper is heated by a heating roller in fixing the toner image. As a result, curl is caused in the paper after fixing processing and therefore, various curl removing means are provided to remove the curl caused in the paper. According to the curl removing means, generally, a method of removing curl is by winding the paper in a direction reverse to the direction of curl, caused during fixing, has been adopted.
For example, it is a general method that in a fixing device, a discharge roller and a pressing roller that is brought into press contact with the heating roller are arranged on the downstream side of a heating roller in the paper feed direction, two auxiliary casters are brought into press contact with the discharge roller, and a reverse curl is provided to the paper on the basis of cooperation between the discharge roller and the respective auxiliary casters thereby removing the curl of the paper.
However, according to the conventional fixing device, in structuring the means for removing curl from the paper, the two auxiliary casters which are brought into press contact with the discharge roller are needed and further, accessory parts, such as a spring, for bringing the respective auxiliary casters into press contact with the discharge roller are also needed. As a result, the cost of the fixing device is increased and the total cost of the image forming apparatus is increased.